JPH0649005A - Simple method for producing vinylglycine (2-amino-3- butenoic acid) and simple method for dividing derivative - Google Patents

Abstract

The invention relates to a three-step synthesis of vinyl glycine (1) using a cheap, commercially available starting material (3-butenenitrile (2)) and using cheap, simple reagents. Also disclosed is a convenient optical resolution of the N-tert.butyloxycarbonyl derivative by papain-catalysed enantioselective esterification in a two-phase system.

Description

Detailed Description of the Invention

The present invention relates to inexpensive, commercially available starting materials (3-
It relates to the three-step synthesis of vinylglycine (1) using butenenitrile (2)) and using inexpensive, simple reagents. It also discloses a convenient optical resolution of the N-tertiary-butyryloxycarbonyl derivative by papain-catalyzed enantioselective esterification in a two-phase system.

The non-protein amino acid vinylglycine has been isolated from fungi and has been shown to inhibit many enzymes. 〔R. Rando, Accounts of Chemical R
esearch 8 , 281 (1975)]. Due to its biological activity, vinylglycine has been the subject of much synthetic research since its first production in 1974. A review was recently published including synthetic studies leading to vinylglycine [L. Havlicek and J. Hanus, Collect. Czech. Chem. Commun. 56 , 136.
5 (1991)]. Most of the methods described for producing vinylglycine require multi-step reaction steps, often involving tedious methods of protection and deprotection reactions.

The present invention comprises the following reaction scheme 1

[Chemical 3] (Reagent i, MeOH / HCl; ii, NaOCl; iii,
OH ⁻ / H ₂ O; iv, (Me ₃ COCO) ₂ O / OH ⁻ ;
v, _{papain, H 2 O / EtOAc, R} 1 OH. ), And a new and surprisingly simple process for the production of vinylglycine as described below. The synthetic method of racemic vinylglycine is extremely simple and does not require a protecting group.

The first step according to Scheme 1 is -20 ° C.
Cheap and easily available allyl cyanide pinner by reacting allyl cyanide and anhydrous methanol in a molar ratio of 1: 1 to 1: 5 at a temperature between + 20 ° C. and + 20 ° C.
(Pinner) Reaction product, methyl-3-butenylimidate hydrochloride (7). Reaction temperatures between −10 ° C. and + 10 ° C. are preferred. The product resulting from this first reaction is methyl N- using sodium hypochlorite.
Converted to chloro-3-butenylimidate (3).

An excess of sodium hypochlorite solution can be used, from an equimolar amount of sodium hypochlorite to 2
Up to a double molar amount is preferable. The reaction temperature is -40 ° C to +4.
It can be in the range of 0 ° C, preferably between -10 ° and + 10 ° C. The product methyl-N-chloro-3
- butenyl Louis Mi dating insoluble organic solvent in water, for example, can be isolated by extraction with CHCl _3, EtOAc, diethyl ether, petroleum ether, hexane and the like. Methyl-N-chloro-3-butenylimidate (3) is converted to vinylglycine (1) via a Neber-like reaction by reacting (3) with aqueous sodium hydroxide. The reaction temperature of this step is −
It may be in the range of 20 ° C to the reflux temperature, preferably in the range of -10 ° C to + 40 ° C. Reaction time is 5
It is within the range of 25 hours, more preferably 10 hours. The product vinylglycine can be isolated using well-known methods such as crystals or chromatography, for example using cation exchange resins.

Further, the vinylglycine (1) produced in the above reaction step is directly in-situ to N-tertiary-butyryloxy (B).
It is also easy to convert to an OC) derivative. Therefore, N
-Chloro-3-butenylimidate (3) is converted to vinylglycine using an aqueous solution of sodium hydroxide by the method described above, and after a reaction time of 5 to 25 hours, more preferably 10 hours, is insoluble in water. An organic solvent, preferably dioxane, is added. The mixture was cooled to -10 ° C to 10 ° C and di-tert-butyl carbonate was added in a molar ratio of 1-15. The reaction mixture is stirred for a further 5 to 50 hours, during which the reaction temperature rises to 30 ° C, more preferably to room temperature. The product (4) is obtained by a well-known method, for example,
An organic solvent immiscible with water, such as ethyl acetate, may be added to the reaction mixture, the pH of the aqueous solution carefully adjusted to pH 2-6 and the product isolated by extraction into the organic phase. The organic extract is evaporated to dryness to give N-butoxycarbonylvinylglycine (4).

The resolution of the N-tertiary butyryloxycarbonylvinylglycine (4) leaves the D- (4) unesterified, whereas the corresponding ester of L- (4) remains.
It can be carried out using an enantioselective enzymatic conversion to (5).

For this purpose, D, L- (4) is not treated with water.
Miscible organic solvents such as hexane, dichloromethane
Etc. and alcohol component R¹OH (R¹= Linear or branched
C ₁~ C₈-Alkyl, preferably C₁~ C_Four-Archi
Le, most preferably C₂-Alkyl)
Dissolve in.

The solution is adjusted to pH 2-6, more preferably pH 4-5.
To the aqueous buffer of. Suitable enzymes are racemic N-
Hydrolases capable of selectively converting one of the two enantiomers of a protected amino acid, such as lipases, esterases and proteinases. Preferred are proteases, most preferred are thiol proteinases such as papain [EC 3.4.22.2].

To avoid unfavorable equilibrium constants when the esterification is carried out in a partially aqueous medium, the enzymatic esterification is carried out in a two-phase system.

The esterification products partition preferentially into the organic phase with respect to the substrate. The new effective equilibrium constant is a function of the partition coefficient of substrate and product between water and organic solvent and the volume of the two phases.

For resolution of the Boc-derivative (4) using papain, the organic phase of ethyl acetate and the ethanol of the esterified alcohol is preferred. The reaction temperature is 15
And 50 ° C, more preferably between 20 and 40 ° C.

The optimum reaction time depends on the reaction conditions, but can be easily confirmed by tracing the reaction using a conventional analytical technique (DC, HPLC, etc.).

Isolation of the product proceeds by separating the organic layer from the aqueous phase and washing the organic layer with aqueous sodium hydrogen carbonate solution. The organic layer was evaporated to dryness to obtain crude ethyl-L-N-protected vinylglycine in greater than 90% chemical, optical yield, which was obtained by conventional techniques,
For example, it can be purified using chromatography. To isolate the DN-protected vinylglycine, the aqueous sodium hydrogen carbonate solution is adjusted to pH 1-5, more preferably pH 2-4 and extracted with an organic solvent. After evaporating the organic solvent to dryness, the crude DN-protected vinylglycine (4) is obtained in high yield and high purity.

Thus, the method disclosed herein provides a simple and inexpensive route to enantiomerically pure forms of L- or D-vinylglycine (useful as chiral synthons).

The present invention includes a Pinner reaction and a Naber rearrangement starting with allyl cyanide,
The present invention relates to a method for synthesizing vinylglycine (1) via a three-step route which produces a racemic form (1). The racemic mixture is then treated with L-and D using papain or a separate suitable enzyme.
It can be resolved into both isomers of-as a Boc derivative.

The invention will be further described by way of examples. In the following example, ¹ H nmr. Using a Perkin Elmer R34 spectrometer at 220 MHz, Brooker A
Performed at 250 MHz using a C 250 spectrometer or 400 MHz using a Brooker WH 400 spectrometer. ^{The 13} C nmr spectrum is based on Brooker WH 4
Measured at 100.62 MHz using a 00 spectrometer.
Mass spectra were measured using a Kurato MS80 mass spectrometer.

Example 1.Methyl 3-butenylimidate hydrochloride Cyanation in anhydrous methanol (10 ml) at 0 ° C under nitrogen
Allyl (3-butenenitrile ((2); 10 g, 15.2 mm
Dry hydrogen chloride gas was bubbled through the stirred solution of ol) for 1 hour.
Cap the flask and stir the contents at 2 ° C. for 12 hours.
It was The reaction mixture was dried with diethyl ether (250 ml).
Dilute, remove the resulting precipitate by filtration, and extract with diethyl ether again.
Wash with (50 ml) and imidate as colorless hygroscopic solid.
The hydrochloride salt (7) (19.28 g, 95%) was obtained. δ_H(220 MHz; heavy water) 5.9 (1H, m, CH = CH₂), 5.25 (1H,
br.d, J 16 Hz, CH = CHH transformer), 5.25 (1H, br.d, J 1
2 Hz, CH = CHH cis), 3.7 (3H, s, OCH₃), 3.17ppm (2H,
d, J 12 Hz, CH₂). ν_max(Nujol grinding) / cm^-1 1669 (C = N). m / z (Cl) 136 ((M + 1)⁺, 10.1%), 122 (5.4), 100 ((M-HC
l)⁺, 100), 86 ((M-HCl-CH ₃)⁺, 47.1), 68 (2.0). m / z (E
l) 235 ((M-HCl)⁺, 2.5%), 202 ((2M + 2-2HCl)⁺, 7.1), 1
85 ((2M + 1-HCl-CH₃)⁺, 16.9), 136 ((M + 1)⁺, 28.7), 110
(39.7), 100 ((M-HCl) ⁺, 100), 93 ((2M + 1-2HCl-CH₃)⁺, 6
3.7), 86 ((M + 1-HCl-CH₃)⁺, 1.2).

2. Methyl N-chloro-3-butenylimi
The date (3) imidate hydrochloride (7) (3.0 g) was added directly to the sodium hypochlorite solution (12-14%, 100 ml) at 0 ° C. The mixture was stirred for 1 hour and extracted with petroleum ether (boiling point, 40-60 ° C., 3 × 30 ml). The extract was dried (MgSO ₄ ) and concentrated under reduced pressure to give N-chloroimidate (3) as a colorless oil (2.95 g,
100%) was obtained. δ _H (220 MHz; deuterated chloroform) 5.9 (1H, m, CH = CH ₂ ),
5.28 (1H, d, J 17 Hz, CH = CHH transformer), 5.25 (2H, d,
J 11 Hz, CH = CHH cis), 3.85 (3H, s, OCH ₃ ), 3.4 ppm (2
H, d, J 12 Hz, CH ₂ ). m / z (El) 134 ((M + 1) ⁺ , 6.9%), 98 ((M-HCl) ⁺ , 20.6), 9
2 (17), 83 (0.7), 69 (100).

3. D, L- Vinylglycine (1) sodium hydroxide solution (0.79 g, 19.8 mmol, 50
N-chloroimidate (3) (0.88 g, 6.6 ml)
mmol) solution was stirred at room temperature for 10 hours. Dowex Solution
50W-XS cation exchange resin column (H ⁺ form, 10
g). The column was washed with deionized water and eluted with a 2% aqueous pyridine solution until the ninhydrin test was negative. The eluate was evaporated under reduced pressure to give DL-vinylglycine.
(1) (0.35 g, 53%) was obtained. Melting point 175 [deg.] C (decomposition). δ _H (220 MHz; heavy water) 5.9 (1H, m, CH = CH ₂ ), 5.45 (1H,
d, J 15.7 Hz, CH = CHH transformer), 5.43 (1H, d, J 12.5
Hz, CH = CHH cis), 4.3 ppm (1H, d, J 9 Hz, CH-CH = C
H ₂ ). δ _C (100 MHz, heavy water) 173.7 (C1), 131.0 (C3), 122.1 (C
4), 57.8 (C2). m / z (Cl) 102.86 ((M + 1) ⁺ , 20.1%), 58 ((M + 1-CO ₂ ) ⁺ , 1.
1), 56 (9.1). (Observed value M + 1 ⁺ : 102.0555 C ₄ H ₈ NO ₂ calculated 102.111).

4. N-third-butyroxycarbonyl-
D, L- Vinylglycine (4) Freshly prepared N-chloroimidate ((3); in a solution of sodium hydroxide (1.079 g) in water (50 ml)).
The solution of 1.1 g) was stirred at room temperature for 10 hours. Dioxane (50 ml) was added and the mixture cooled to 0 ° C., di-third
Butyl dicarbonate (2.14 g) was added and the mixture was stirred for 8 hours, the cooling source was removed and the temperature was allowed to gradually rise to room temperature. Dioxane was removed under reduced pressure and the residual solution was extracted with ethyl acetate (10 ml). Ethyl acetate (15 ml) was added to the aqueous phase. Aqueous phase pH 2 (1M
KHSO ₄ ) and further extracted with 15 ml of ethyl acetate. The organic extract was washed with saturated sodium chloride solution (15
ml), dried (MgSO ₄ ) and concentrated under reduced pressure to give derivative (4) (1.11 g, 50%) as a colorless oil. δ _H (220 MHz; deuterated chloroform) 7.1 (1H, m, NH), 6.0
(1H, m, CH = CH ₂ ), 5.45 (1H, d, 19 Hz, CH = CHH transformer), 5.30 (1H, d, J 10 Hz, m, CH = CHH cis), 4.87 (1H,
_{m, CH 2), 1.41 (} 8H, s, t-Bu). δ _C (100 MHz, deuterated chloroform) 174.5, 173.5 (C1), 15
6.7, 155.2 (C = O Boc), 132.6, 132.2 (C3), 117.5 (C4),
81.6, 80.3 (C-Me ₃ Boc), 57.0, 55.6 (C2), 28.1 (CH ₃ Bo
c). m / z (Cl) 202 ((M + 1) ⁺ , 2.4%), 163 (20), 146 ((MC
^{_{4 H 8) +, 65)}} , 102 ((2M-CO 2 C 4 H 8) +, 4.9), 86 (0.6). (Actual value M + 1 ⁺ : Calculated as 202.1067 C ₉ H ₁₆ NO ₄ : 202.22
7). m / z (Cl) 202 ((M + 1) ⁺ , 20.1%), 58 ((M + 1-CO ₂ ) ⁺ , 1.1),
56 (9.1). ν _max (chloroform) / cm ^-1 1720, 1510, 1465.

5. Ethyl N-tert-butyroxycarboni
Resolution of ruvinylglycinate (4) papain (Sigma, type II, 0.3 g) in citrate-phosphate buffer (1 M, 15 ml, pH 4.2), L-cysteine (45 mg), EDTA 4 sodium salt ( 1M, 75
μl) was stirred for 10 minutes. Racemic N-tert-butyloxycarbonyl-D, L-vinylglycine ((4); 0.5 g, 2.5 mmol) dissolved in a mixture of dichloromethane (3 ml) and ethanol (2 ml) was added. The mixture was stirred at 37 ° C for 2 days. The mixture is filtered (celit
e ^R ) and washed with ethyl acetate (10 ml) and water (10 ml). The organic phase was separated, ethyl acetate (10 ml) was added, and the aqueous phase was carefully acidified with potassium hydrogen sulfate (1M) to pH 1 (Congo red). The mixture was shaken and the combined organic layers and washings were washed with sodium hydrogen carbonate solution (5%,
2 × 5 ml), washed with water (10 ml) and saturated sodium chloride solution (10 ml) and dried (MgSO ₄ ).
And concentrated under reduced pressure. Petroleum ether (boiling point, 40-60 ° C): ethyl acetate (10: 1) with the residue as eluent
Purified by flash chromatography using
Ethyl L-N-tert-butyloxycarbonylvinylglycinate (5) (0.2 g, 70%) was obtained as an oil. δ _H (400 MHz; deuterated chloroform) 5.83 (1H, ddd, J 17,
14,7HZ, CH = CH ₂ ), 5.35 (1H, dd, 17.1,8Hz, CH = CHH transformer), 5.30 (1H, dd, J 10.3, 1.7 Hz, CH = CHH cis),
4.8 (1H, m, CH), 4.17 (2H, q, J 7.1 Hz, CH ₂ CH ₃ ), 1.4
1 (9H, s, t-Bu), 1.23 (3H, t, J 7.1 Hz, CH ₂ CH ₃ ). δ _C (100 MHz, deuterated chloroform) 170.6 (C1), 154.7, 15
5.2 (C = O Boc), 132.7 (C3), 117.0 (C4), 79.9 (C-Me ₃ Bo
c), 61.6 (C2), 55.7 (CH ₂ Et), 28.1 (CH ₃ Boc), 14.0 (CH ₃
Et). m / z (Cl) 230 ((M + 1) ⁺ , 0.8%), 174 ((M + 1-C ₄ H ₈ ) ⁺ , 18.
2), 156 (13.8), 130 ((M + 1-C ₄ H ₈ -CO ₂ ) ⁺ , 9.2), 100 ((M + 1
-C ₄ H ₈ -CO ₂ -C ₂ H ₅ ) ⁺ , 23.1), 158 (2.8%), (Actual value M +
1 ⁺ : calculated as 230.1394 C ₁₁ H ₂₀ NO ₄ : 230,277). ν _max (chloroform) / cm ^-1 1770, 1712, 1495c
m ^-1 .

The organic layer was washed with saturated sodium chloride solution (10 m
washed with l), dried (MgSO _4), and concentrated under reduced pressure D-N-tert-butyloxycarbonyl vinylglycine (6) (0.24 g, to obtain a 90%).

Boc group-deprotection using standard reaction conditions (trifluoroacetic acid) yields the corresponding amino acids with high enantiomeric purity: L-vinylglycine {(S) -2-amino-3-butenoic acid}: [Α] _D = + 94.7 ° (H ₂ O, 25.8 ° C., c =
0.25) _D -vinylglycine {(R) -2-amino-3-butenoic acid}: [α] _D = -96.3 ° (H ₂ O, 22.9 ° C, c =
0.46).

Claims (5)

[Claims] 1. A method for producing vinylglycine consisting of (a) starting reagent 3-butenenitrile (b) Pinner reaction (c) substitution of NH with NCl (d) subsequent Naber rearrangement by base contact . 2. Reaction scheme 1 below:(In the formula, i represents MeOH / HCl; ii represents NaOCl
Iii is OH^-/ H ₂Claims characterized by
The method according to item 1. 3. The reaction step according to claim 2 is represented by the following reaction scheme: (Wherein V = H ₂ O / EtOAc, hydrolase in R ¹ OH, where R ¹ = linear or branched C ₁
-C ₈ - alkyl, more preferably C ₁ -C ₄ - alkyl, most preferably C ₂ - alkyl) of N-
A process for the preparation of L- or D-vinylglycine in enantiomerically pure form, which comprises prolongation by enzymatic resolution via enantioselective esterification of tertiary butoxycarbonylvinylglycine. 4. The method according to claim 3, wherein the hydrolase is lipase, esterase or proteinase. 5. The method according to claim 4, wherein the hydrolase is a protease, preferably a thiol proteinase.